This invention relates to a method and apparatus for molding a container. More particularly, but not by way of limitation, this invention relates to an apparatus and method for molding a container that has a closed end and an opened end, and wherein a material may be placed therein followed by the closing of the open end.
The injection molding of plastics is used to create a number of different objects such as caps, lids, and other plastic components. The prior art injection molding will consist of melting a plastic into a fluid state and injecting the liquid plastic into a mold. The mold will generally consist of a first section and a second section. The first section and the second section cooperate to form a mold cavity. The liquid plastic is injected into the mold. Thereafter, the liquid plastic is allowed to cool. The molded plastic article is then ejected from the mold, as is understood by those of ordinary skill in the art.
Prior art patents such as U.S. Pat. No. 5,560,939 to Nakagawa entitled xe2x80x9cMOLD ASSEMBLY COMPRISING A SLIDING MOLD INSERT ADAPTED FOR AUTOMATED INSERTION AND REMOVALxe2x80x9d provide a mold insert that is reciprocally movable with the mold insert coupling portion. Also, in U.S. Pat. No. 5,346,659 to Buhler et al entitled xe2x80x9cMETHOD FOR PRODUCING A WELD-LINE FREE INJECTION MOLDED PLASTIC CONTAINER BODY PORTIONxe2x80x9d, the inventor describes an injection molding mechanism and method of its use for the formation in a single sequence of operation of weld-line free cylindrical container body having a central opening at one end. In yet another prior art device, U.S. Pat. No. 5,139,714 to Hettinga teaches a process for injection molding a hollow plastic article in which a low pressure heat-activated gas is injected in combination with a plastic material into a mold cavity of a plastic injection mold unit.
Despite these prior art molding techniques, there is a need for a mold apparatus and method that will produce a container that generally includes a closed end, an opened end, and a hollow inner member that can hold materials. For instance, the container may hold a medicine such as a drug in tablet form. Alternatively, the container may be capable of holding medicine in liquid form. After placement of the medicine within the container, the open end may be closed according to prior art techniques such as a heat seal.
A device for molding a container is disclosed. The device will include a first member including an opening defined therein. A manifold member operatively attached to the first end of the first member for channeling a plastic fluid to an insert means is included. The insert means are positioned within the opening located within the first member, with the insert containing a first slide and a second slide. The first slide and second slide will have an extended position and a contracted position, and wherein the contracted position defines a cavity profile.
The second member will have a first end that contains a plurality of core pins. A piston is adapted to the second end of the second member for reciprocating the second member into engagement with the insert so that the first slide and second slide are moved to the contracted position. During the reciprocating motion, the plurality of core pins are received in the cavity profile. The apparatus will further comprise heater means for suppling a heat to the manifold means so that the plastic remains fluid. In one embodiment, the manifold member comprises a first plate with a first channel therein for channeling the plastic fluid therethrough and a second plate with a second channel therein cooperating with the first channel from the first plate for channeling the plastic fluid to the insert means.
The apparatus will further contain a first water supply means connected to the insert to supply a water to the insert. The apparatus will further contain a second water supply means connected to the first member. In the preferred embodiment, a cast heater element, operatively attached to the heater means is positioned within the first member so that the plastic fluid is heated before entering the insert. The water supply means may also connect to the first slide and to the second slide.
The apparatus may further comprise a first spring means, operatively associated with the first insert, for biasing the first slide outward from the opening, and second spring means, operatively associated with the second insert, for biasing the second slide outward from the opening. In the preferred embodiment, the reciprocating member comprises a piston operatively attached to the second member and wherein the second member comprises a retainer plate operatively attached to the piston and a stripper plate being operatively attached to the piston, the stripper plate being selectively detachable from the retainer plate. Also, a third water supply means for supplying a water stream to the core pins, and a fourth water supply means for supplying a water stream to the retainer plate is included. The apparatus may further comprise a second insert, with the second insert being biased with a second spring means, operatively associated with the second insert.
Also described herewith is a method of casting a container with a mold. The mold will include a first member that has an opening defined within a first end. The mold will further include a manifold member operatively attached to the first end of the first member for channeling a plastic fluid to an insert means. The insert means is positioned within an opening located within the first member, the insert means containing a first slide and a second slide, with the first slide and second slide having an extended position and a contracted position.
The mold will also contain a second member having a plurality of core pins contained thereon; and, a piston adapted to the second member for reciprocating the second member into engagement with the insert means. Therefore, the method comprises heating a plastic so that a plastic fluid is formed, and thereafter channeling the plastic fluid into the manifold. Next, the plastic fluid is heated within the manifold and the plastic fluid is channeled through the first member and into the first slide and second slide. Next, the piston is moved so that the second member contacts the first slide and the second slide which in turn causes the contraction of the first slide and the second slide so that a cavity profile is formed. The core pins are placed into the cavity profile. The method allows for the injection of the plastic fluid into the cavity profile, and in turn, casting the plastic fluid about the core pins so that a container is formed.
In one embodiment, the first member further comprises cast heaters operatively associated with the first and second slide, and wherein the method further comprises heating the plastic fluid with the cast heaters, and wherein the step of channeling the plastic fluid through the first member and into the first and second slide includes flowing the plastic fluid through the cast heater so that the plastic fluid is maintained at a constant temperature.
The method further comprises introducing a first water stream into the first slide and introducing the first water stream into the second slide. The first water stream is circulated within the first member, and then exited from the first member. A second water stream may be introduced into the core pins, and the method includes circulating the second water stream within the core pins. Next, the second water stream is exited from the plurality of core pins. In the preferred embodiment, the temperature of the plastic fluid within the manifold is measured. The temperature of the heater is adjusted in order to maintain the fluidity of the plastic. The method may further include measuring the temperature of the plastic fluid within the first slide and the second slide and adjusting the temperature of the cast heater in order to maintain the plastic fluidity.
The mold may further contain an ejector plate operatively associated with the second member. The method further consist of reciprocating the piston away from the first end of the first member and allowing the first slide and second slide to expand. Next, the piston is reciprocated so that the ejector plate traverses the plurality of core pins so that the container surrounding the core pins is ejected.
The method may also include filling the container with a material. The material may be a drug in tablet form, or alternatively, the material may be a drug in a liquid form. A precise amount of material may be placed within the container. After the material is placed therein, the method may further include sealing the container by sealing the open end of the container.
An advantage of the present invention includes the production of a hollow plastic article. Another advantage is the production of a container having a first end that is closed, and a second end that is opened. Yet another advantage is that after processing, the container can be filled with a material; thereafter, the open end may be sealed. Another advantage is that the material to be placed within the container may include a drug in liquid form or tablet form. Still yet another advantage is that an exact amount of the material (such as a pharmaceutical prescription) may be added into each individual container, and thereafter sealed. Another advantage is the use of a resin that allows for suitable flow properties during injection. Yet another advantage is the process leaves a small seam parting line about the produced product.
A feature of the present invention includes having a mold that contains a first stationary mold half and a second traveling mold half. Another feature of the present invention includes use of a sliding insert which is constructed in two cooperating halves. The sliding insert is fitted into an opening within the stationary mold half Yet another feature includes the sliding insert is biased within the opening so that there is an expanded position. Another feature includes that the sliding insert may be biased into a contracted position by the traveling mold half.
Another feature includes a cavity profile is formed when the sliding insert is moved to the contracted position. In the preferred embodiment, the sliding insert contains a plurality of cavity profiles. Another feature includes a core pin is positioned on the traveling mold half, with the core pin being sized as to fit into the cavity profile. Still yet another feature includes a plurality of core pins may be attached to the traveling mold half, that cooperate with the cavity profiles of the sliding insert. Still yet another feature includes the core pins within the cavity profile form an annulus into which the plastic fluid is injected.
Yet another feature is the application of heat means to heat the manifold in order to keep the fluid plastic at the proper temperature. Another feature is the application of cast heaters to keep the plastic fluid at the proper temperature within the cavity profile during injection. Still yet another feature includes use of a water stream that cools the sliding inserts. Another feature is the use of a water stream injected within the core pin in order to cool the core pin. Yet another feature is having a free standing core pin that is not anchored within the cavity profile during the injection process.